I have the impression that this decision will become useful in other fields too. The Register reports:

General ideas and structures behind computer games and programs can
be copied as long as the source code and graphics are not, the UK’s
Court of Appeal has ruled.

Judge Jacobs said:

"If protection for such general ideas as are relied on here were
conferred by the law, copyright would become an instrument of
oppression rather than the incentive for creation which it is intended
to be," said Jacobs. "Protection would have moved to cover works merely
inspired by others, to ideas themselves."

Did somebody say patents? But game rules cannot be patented. There is something useful for our cause here.